The present invention relates to a communications system and method and, more particularly, to a signal distribution system and method for switching and connecting cells in a communications network.
The use of a switching matrix for wireless communications systems based on distributed antennas is disclosed by Motley et al. in U.S. Pat. No. 5,682,256. Motley et al. uses a switching matrix to interconnect a number of base stations on the input ports to a number of distributed antennas on the output ports. The switch matrix allows any combination of inputs to be connected to any combination of outputs so that base stations can be connected to antennas in a very flexible manner. This allows wireless services such as cellular radio to be delivered to users with significant cost savings for network operators. The benefits of using a switched distributed antenna system are outlined for example in a paper by Wake and Beacham, “Radio over fiber networks for mobile communications”, Proc. SPIE, vol. 5466, 2004.
The links between the switch matrix and the distributed antennas are accomplished in Motley et al. using optical fiber cables using a technique known as radio over fiber. Radio over fiber has many advantages for this type of network with high quality transmission and low signal attenuation as a function of distance being the primary ones. However, there are situations where optical fiber cables are not available at economic cost at places where they are required. An example of this type of situation is a city center where the local telecommunications operator does not provide ‘dark’ fiber cables, i.e., fiber cables that are not part of a managed service.
Chu et al., in U.S. Pat. No. 5,890,055, discloses the use of wireless repeaters in a distributed antenna system (DAS) with a fixed configuration. This architecture avoids the problems of fiber availability described above. However, the fixed configuration described by Chu limits the operational benefits of a switched approach.